Final answer:
A pull factor for European immigration to the U.S. was the availability of industrial jobs. Nativism influenced federal policy by prompting more restrictive immigration laws due to concerns over cultural differences.
Step-by-step explanation:
1. The pull factor that influenced European immigration to the United States is best described by option B) industrial jobs. The expansion of industrialization in America created a high demand for workers, which attracted immigrants from Europe seeking employment opportunities in various sectors such as textile factories, shipyards, and coal mines.
2. The role of nativism in federal policy is encapsulated in option D) concern over cultural differences led to more restrictive immigration laws. Nativism, characterized by a preference for native-born individuals and a fear of foreign influence, significantly swayed America's immigration policies in the 1920s leading to legislation such as the Emergency Quota Act of 1921 and the Immigration Act of 1924, which aimed to restrict the flow of immigrants from certain regions, thereby reflecting the discriminatory attitudes of the time.